Similar to the benefits that the primary care and pediatrics fields have enjoyed following years of rapid strep and flu testing, the uptake of rapid, single-use, point-of-care (POC) testing in optometry helps to guide clinical management and therapeutic decisions.
One of the pioneers of POC testing for eye care professionals is RPS Diagnostics, which developed a suite of cost-effective POC diagnostic test kits based on a patented immunodiagnostic technology platform. These tests include InflammaDry to detect elevated levels of MMP-9, a nonspecific inflammatory marker that has consistently been shown to be elevated in the tears of patients with dry eye disease, and AdenoPlus, a rapid test for detecting adenoviral conjunctivitis. These POC tests enable eyecare providers to more accurately diagnose ocular disease, provide appropriate and timely treatment, and reduce the costs associated with spread of disease, unnecessary treatment methods, and patient dissatisfaction.
InflammaDry and AdenoPlus were acquired by Quidel Corporation from RPS Diagnostics in May 2017.
Testing for MMP-9
The InflammaDry test identifies patients with elevated MMP-9, which represents clinically significant ocular surface inflammation. Matrix metalloproteinases are proteolytic enzymes that are produced by stressed epithelial cells on the ocular surface.1
MMP-9 destabilizes the tear film and directly contributes to corneal barrier dysfunction by breaking down tight junctions and facilitating inflammatory cell migration. This ultimately leads to corneal staining, rapid tear break-up times (TBUT), ocular discomfort, and fluctuating vision.1 MMP-9 is the ideal biomarker for ocular surface inflammation because it elevates early, catalyzes the development of IL-1 and TNF-α, and accumulates as part of the persistent cycle of inflammation.
Unfortunately, traditional dry eye testing methods (TBUT, Schirmer’s, osmolarity) cannot determine which patients have clinically significant inflammation.2 Sambursky and colleagues showed that MMP-9 was positive (≥40 ng/ml) only 53 percent of the time in symptomatic dry eye patients.3 Lanza and others measured TBUT, Schirmer’s, osmolarity, and MMP-9 in 110 patients with dry eye symptoms and determined that 39 percent were positive for elevated MMP-9. No statistical difference was found in the profile of dry eye patients that tested positive or negative for elevated MMP-9 based on symptoms and signs.3 Furthermore, Tong and colleagues showed that tear inflammatory mediators including MMP-9 did not improve after punctal occlusion.4
The presence or absence of ocular surface inflammation helps to guide therapeutic decision-making in patients with symptoms of dry eye.3 Artificial tears provide palliative relief of eye irritation in patients with aqueous tear deficiency but do not reduce MMP-9 levels or reduce inflammation in chronic dry eye.5 Patients with confirmed inflammation benefit from chronic anti-inflammatory therapy.5,6
Repeated InflammaDry testing after initiation of therapy can confirm an adequate therapeutic response or suggest that additional and/or more aggressive anti-inflammatory regimens are required. Punctal occlusion should be reserved for patients without inflammation or performed after the inflammation is controlled.4